Line sequential color television apparatus



March 20, 1956 LINE SEQUENTIAL COLOR TELEVISION APPARATUS Filed Maron 14, 1950 G. E. SLEEPER, JR., ET AL 8 Sheets-Sheet l BY MM AAA/4 ATTORNEYS March 20, 1955 G. E. SLEEPER, JR.,4 ET AL 2,739,181

LINE SEQUENTIAL COLOR TELEVISION APPARATUS Filed March 14, 1950 8 Sheets-Sheet 2 P4 77E/FN W/T/ ZEO S19/F7' March 20, 1956 G. E. SLEEPER, JR., x-:TAL 2,739,181

LINE SEQUENIIAL COLOR TELEVISION APPARATUS Filed March 14, 1950 8 Sheets-Sheet 5 o 3 0 3 I mf uuuuuuuuu Uwuuwis amr/f W 43 42 am@ 45 WUI l I f 50 W M' Ww 16m U MM MMM u ll--u Il u Hmm TTM.

M W wf TW ffwuuuuuuuuum EUHHUTW wmf PULSE j 'W I T- I-J-LJ-I--I-I-L INVENTORS ATTORNEYS March 20, 1956 G. E, SLEEPER, JR., ET AL 2,739,181

LINE SEQUENTIAL COLOR TELEVISION APPARATUS 8 Sheecs-Sheet Filed March 14. 1950 kns BYC/

March 20, 1956 G. E. SLEEPER, JR., ET AL 2,739,181

LINE SEQUENTIAL COLOR TELEVISION APPARATUS 8 Sheets-Sheet 5 Filed March 14, 1950 INVENTORS 500rg@ fleeelf, f1,

ATTORNEYS NNN Bmw

LLL,

G. E. sLEEPER, JR., ETAL 2,739,181

March 20, '1956 LINE SEQUENTIAL COLOR TELEVISION APPARATUS 8 Sheets-Sheet 6 Filed March 14, 1950 INVENTORS MMM Num.

mmm.

ATTORNEY` March 20, 1956 G. E. SLEEPER, JR., ET AL 2,739,181

LINE SEQUENTIAL COLOR TELEVISION APPARATUS Filed March 14, 1950 8 Sheets-Sheet 7 wie a U U U U U j.) U

Y Y Y Y Y Y Y- c' 7 Y Y Y Y Y Y- d l/ V W v lf l/ f l L' jU U U i Y Y Y .n Y T Iz Y T U U p U LI U 1| LI W za Y if if 7* BYWW xfm'f ATTORNEYS March 20, 1956 G. E. SLEEPER, JR., ETAL 2,739,181

LINE SEQUENTIAL COLOR TELEVISION APPARATUS Filed March 14, 195o a sheets-sheet a www .O WQ. MR h. A. W wk. .l/ han En. wwww mw m9 z: :if T .N lu MSF@ V. mb

United States Patent v LINE SEQUENTIAL COLOR TELEVISIN APPARATUS George E. Sleeper, Jr., Berkeley, Robert J. Stahl, Redwood City, and Carl Frederick Wolcott, Beverly Hills, Calif., assignors to Color Television Incorporated, San Francisco, Calif., a corporation of California Application March 14, 1950, Serial No. 149,577 4 14 Claims. (Cl. 17E-5.2)

1949, for an invention entitled Multicolor Television,`

has set forth a proposal of television apparatus usable for the transmission and reception of color television image signals. line-sequential principles. tion made clear the fact that the principles upon which line-sequential operations are controlled may apply generally also to other forms of transmissions and reception when line color shift is used.

It is also vdisclosed in the aforesaidU. S. patent apiV plication that television apparatus functioning under the heretofore known so-called line-sequential principles make possible the creation of image representations at receiver points in limited detail of the tricolor." This is because the prior art lacks color shift and each line of the picture being re-created alwaysappears in the same color. l

Television transmissions in black-and-white are standardized in the United States in such a way that each This system operates in accordance with The aforesaid patent applican line will be in the same color.

rice' fields per'second are re-created to form thirty pictures, l

the color detail in a vertical direction will be found to be reduced. This is because of the fact that if an assumption be made that the scanning of the first line of the first field is in red, then each succeeding sixth Likewise, the third line of the first field scanned and each sixth line thereafter will appear in the second component or primary color, namely green. The fifth `line and each sixth line thereafter will appear in the third component or primary color, namely blue. In the next field scanned which, under the assumed conditions, will represent a trace of all even lines of the pictures, line two of the even field will ordinarily be re-created in blue, while line four will be in red, and line six will be in green. Each sixth line of the picture is of like c olor in the scanning pattern.

Still following the principles of black-and-white transmission, and with the same standards, it will becomeA apparent that the color in which the lines of the third field will be scanned is a duplication of the color line scanning order of the first field. Similarly, the color A, red, green, blue, and so on, as in the prior art, the` created picture consists of 525 picture lines (neglecting blanking periods) which are interlaced in a 2:1 relationship. These picture lines are caused, in most sysl tems, to appear as traces on the end of a cathode ray image-producing tube target or screen which may be viewed directly (as in the case of many presently marketed television receivers) or indirectly (as by projection methods in connection with other types of television receivers). Utilization of line-sequential principles of television Vscanning in tricolor operations, in-

the case of interlaced transmission or reception of the image signals, means that a scanning of the television picture occurs inV such manner that adjacent lines of the color representation of each picture field shallapl' pear in successive picture frames in different colors of a chosen color cycle. The color cycle under such circumstances consists of the primary colors used for color analysis at the transmitter and for color image re-creation at the receiver. Various color primaries may be chosen. For illustrative purposes in connection `with this disclosure the primary or component colors will be considered as being appropriate values of red, green, and blue. The color cycle of transmission and reception may be of the order red, green, blue, red, and so fOIlIi.V

Following these principles of prior art line-sequential operations and conforming substantially also to the nowstandardized black-and-white standards of reception, where the S25-line pictures interlaced in the 2:1 relationship are transmitted in such a way that sixty image line scanning order of the fourth field will duplicate l the second field. Consequently, each line of the recreated picture is definitely assigned to one particular color so that in the finally-observed picture, three pic` ture lines are required to trace the three selected colors. The George E. Sleeper, Jr., patent application, Serial No. 121,861, hereinabove mentioned, has disclosed suitable apparatus and circuits for bringing about a shiftin L the color scanning order of the different lines of the picture. "Instead of restricting the color scanning for each picture line to one color only as with prior art i systems, a color shift is introduced into the operation. This produces a change in the color initiating the color cycle. Thus, assuming one form of color shift to take place, provision might be made whereby in the third field scanned, the operation would be substantially like that above mentioned for the first field. Instead of starting the first line of the third field in red and then scanninglines 3, 5, 7, 9,' and so forth in green, blue,

color 1 cycle will be maintained,` but line 1 would be scanned, for instance, in green (it was in red in the first field). The maintained color cycle then places lines 3, 5, 7, 9, andso on in the colors blue, red, green, blue, and so on.

This type of operation increases :to a considerable extent the color definition in a vertical direction because it now makes possible the creation of different color values for the same picture lines. The resultv is that the introduced color shift in -the form of the single line shift (as above described and likewise set forth in the above mentioned U. S. patent application Serial No. 121,861) scans like lines of the picture in two colors of the color cycle. This provides twice the vertical color detail obtainable where no shift in color scanning of the chosen lines is introduced.

Likewise, as defined in the mentioned pending patent l application, the introduction of a double line shift provides for scanning all picture lines in all colors. This naturally increases still further the vertical color definition.

If now the field scanning rate is maintained at sixty fields persecond, as for standard blackand-white operations, it can be seen that regardless of which method above-discussed happens to be used, a picture of 525 lines formed from two separately scanned fields, each of half the number of picture linesof the total, will be traced each lo second, with the separate field scannings accomplished in l@ second. However, in the lo sec` ond time period, it is not possible in the allotted band- -width, and for present standards, to trace all picture lines scribed pattern of line-sequential color) the re-created.

image isreproduced' in precisely the same. manner andi line relationship each/o second. For conditions of single line shift, it^can be appreciated thateach lmsecond" each. picture line has been scannediin twocolors. Lastly, for conditions of'double line color shift'ineach.. V16 second, each line of picture is scanned inail" three colors ofthe tricolor.

To achieve ythe various types of`.color shift' hereinabove proposed, the apparatus and system described'. by the aforesaid. U. SI patent application of George El Sleepemlr., operated'to bring about the. color shift. by reason of a control"(in the illustrated form) ofithe de.- ection amplitude of'theline scanningutrace. ofjthe., cathode ray beam across the image p roducingtubetarget., Such a target may be the luminescent screen ofa cath-A ode ray image-reproducing tube or the mosaic-responsive image-receivingltarget.ofa cathode ray, camera tube,` for instance. Suchcontrol. always.. is, effected during blankingperiods so that no shift' .occurs while. the.beam.trace is actually viewedl.

One ofthernost convenient arrangementsto provide fonline-sequential frmsoftelevision scanning operations; is to havev the image-transmitting tube target or the re,- cei'ving tube. target formedorv divided intocontiguons.. areas. Eachareagis ofjstandard aspect ratio... Eachis. arranged'side. by side with respect to each other.. The cathode ray scanningy beam in its deflectioniscausedLto tracefrom the first area to the second to thezthird and. then snap backto the first area. The receivertubetargetinfsuchasystemalso consists of threeareascoatedA with different phosphor-s or other. substancesproducingg. luminous. effects undery electron beanrimpact. Impact of the.. scanning electron beam as it is modulated. by received signals produces` ony one target section. a.` line.l image in one color. After this has been accomplished,-. the continuedlateral sweep of the scanning cathode ray beam, after, an interruption corresponding-to.theblanlcfing period,vmoves.= over upon a second color-responsive:- area. At.this.areaxthe next picture line istraced ini a. diferentcolor. Next, the beamtracefis,blanked,.after: which the beam movesinto the third.coatedarea.to;proe duce the next picture linev in.the third component'or.n primary. color.

This means thatltheftime:periodoveitwhich; the scam.` ning, beamV tracesv eachtarget sectionrepresenting one. color. is,` equivalent nto. that required for. one: line.- ofiscani ning. of ablack-.and-white. picture. Consequently, under.' existing-i black-.and-White4 standards, the scanning'. beann. for. the. color. television. line-seculential` operation, isf. caused. to: move; across onetargetseetionrin 1,4575@ see-1 ond, precisely'the time-period allotted forv scanning-one.' line'.` of a; blackfandrwhite.. image. Where. theree are .cons tiguously-positioncd component lcolor-responsive areas-:oir a tube, the. scanning beam moves fromrone colored'lareaV tofthe^next and iinally'traces one line in" each' of threeV areas. This requires, forgthe three colors, the same'ttime'v period. as f thatnecessary. to' trace three successiveelinesy vof a blackfand-whiteiimage. The-scanning arrangementforv normal black and'. whiteis such that .signals produced 'upon a black-and-'whitaimagefproducing tube-doy not usually spread over a plurality of adjacent areas having differa entiphosphorszbutztrace` successive lines ofthe now-'stand'- ardizedzblackaand-:white pattern on a' tube.A Thisfbeing done,- a' blaclC-.andwhite image results.

If,' however, color transmissionv withcolor shift` isf utilized, then, as noted'inl the. patent applicationabovc' mentioned,.the control of the color scanning:patterniisf brought..aboutthrough theeXercise-of a speeialcontrol' upon.- thef lineor horizontal scannin g.y beam; motion.` The:y color shift. is. brought about by modifying. thescanning? beam deflection` in its l lateral. motion. within 1 thercathode:`

period' continues through the time to transmit the long.

ray tube. Instead of permitting the beam to be deflected in-aelinear-path'to scaneone'line-of all the-red; the'green; and the blue phosphors, the scanning beam is caused to move, for instance, across the red, the green, and a part of the blue (for example, half of the blue) and snap back to recommence the scanning of the red area. Then, to eiect one complete line of color shift,the same procedure occurs vagain so that for: two lateral defiections, for instance, only five-sixths of the lateral sweep of the three' separate image-.areas is. traced, but, as far astbe. overall scanning operation. is conccrned,. theVv scanning beam is :shifted inl position in such" a way that relative to other events tal/.ing place, a' one-lineshift is made; in the color scanning. These shifts occurduringthe .period of vertical blanking as standardized in television transmission where vertical blanltingr was initiated precisely as defined by presently adopted Standards of Good Engineering Practice ConcerningTelevision Broadcasting Stations as published by the FCC and effective December.v l9',' 1945;

Starting substantially coincidentally with the' formation of certain equalizing pulses, the vertical`. blanking vertical deflection control pulses and then through a period over which certain additional equalizing pulses and other linesync pulses were4 sent out. The standardsestablish th'atvertical.blankingl shall'be for a periodof 0.05V, to,

which a supplemental time period represented by 0.03V`

may. be added.' The letter V'in this formula representsv the. time between the commencement ofone fieldscanning andthe commencement of the next succeeding field scanning.l Thus, a period of 0.08V for a S25-line picture occupies- 2l lines of' a black-and-White transmission. time within which to bring about two separate oscillatory controls of deflection in a horizontal or line-scanningV directionand, as explainedin the aforesaid U. S. patentapplication,.color shift may be introduced in this portionofthe operational cycle.

The present .invention likewise is concerned withways and. means to effectcolor shift. instead of.controlling color shiftby modifying the scanning operation in the high speed deflection direction, as for the line deflection. control, this. invention aims. to disclose ways and means in.. which the-scanning beam deflection is controlledin. its slow speed-direction, or in its. vertical or field. detiectionpath.. For someY conditions of operation.. greatly improved operational stability is" obtained.

Inaddition, Ereceiver land transmitter. components are. sim-- onlyI color. receiver. deectionsA at times; when, a color phase: change; isV to be initiated.y ToV bring about.thisr modification.- ofdefiection of, the scanningbeam pattern.

inthe colorzreceiverasthe scanning-.beam'is being. moved laterally in;tl1e;higl1`;speed;or line-deflection pattern, the.

controLhasto beexercised upon the: scanning beam. (if

the: shift is, accomplished within the vertical blanking period) in a time period sometimes as short as two-tl'iiros of:v therhorizontal: deficction. cycle-.and .usually not greater than -vefsixthszof such period; This 'often'. means. that in theflineadeflection oscillator it.is.dift1cultto controlsta.- bilityybecause it is. not particularly susceptible. to any abruptt modification' of its; functioning, and: particularly Inany case, this 2lfline periodprovides. ample.

so when the modification is to occur at such an early time in its operative cycle. Therefore, particularly in transmitter fringe areas and in areas of particularly noisy signal reception, or in areas where particularly bad multipath or ghost image signals tend to reach receivers, deflection stability in a horizontal or line direction tends to be lost during the relatively short period of vertical blanking. The instability is noted mainly in the upper part of the re-created image, which tends to tear out until operation becomes better stabilized at a later part of the cycle.

By taking recourse to the present invention by which a control of the color shift is exercised in accordance with a change in the operation of the vertical or low-speed field deflection, any shift of as much as one line becomes an extremely small percentage change in the operation cycle of the low-speed or vertical field deflection generator. As an example, a shift of one line in the vertical oscillator period means only one (1) part in 2621A by present standards. 'Such a shift is thus easily achieved. A one-line shift in the horizontal or line oscillator is a shift of one part in three, where three adjacent images are scanned. Such a shift is difficult to obtain at all times.

It will be appreciated that color shift changes the color-scanning order by a net advancement or retardation of a single line. Therefore, if the vertical deflection of the scanning beam can be controlled in such a way as to start at a time period equal to one or even two horizontal scanning lines early or late, the color shift can be readily accomplished. For example, considering present transmission standards of a S-line picture re-created at a rate of thirty picture frames per second interlaced by 2:1, there will be produced during each vertical deflection of the scanning beam 262% picture lines per field. These will occur in a j,tm-second time period. Consequently, under presently-standardized operations for television of black and white, there is produced each 2%@ second a series of vertical deflection control impulses. Because of the timing relative to the horizontal deflections these deflections cause the successively traced image fields to interlace. For the odd picture fields the odd picture lines, such as 1, 3, 5, may be assumed to be traced. For the even fields the even lines, such as 2, 4, 6, 8, and so on are assumed to be traced, By reproducing these picture fields in sequence, the picture lines appear to follow in order or are interlaced; the picture detail is improved; flicker effects are greatly reduced; a more efficient picture reproduction occurs; and a better bandwidth utilization for a selected picture detail is established.

If now the vertical deection is caused to occur after only 2611/2` lines in the vertical direction with the color operation of scanning continued in the established color cycle of red, green, blue, red, and so on, it can be appreciated that instead of line 2 of the second field being traced in blue as would be the case where line 1 of the,

first field started in red (by the above illustrated exarnple) and the assumed color cycle here in effect, the scanning operation would be such that line 2 of the second field would be traced in green because the vertical deflection took place one line ahead of its normal operation. On the other hand, if the vertical deflection took place after the scanning of 2631/2 lines of the first field, line 2 of the second field would be traced in red rather than blue because the vertical deflection was one line late. If the vertical deflection took place precisely after 262%/2 lines and line l of field 1 were started in red, then line 2 of field 2 would be re-created in blue. The delay of two lines would be equivalent to an advance of one line. Such reference to traced as is included in this paragraph and the description as a whole` is intended to refer to'coming within the visible window of image reproduction, which, of course, means the picture lines are traced outside the normal blanking period.

The change of a one-line period over which `the vertical deflection control is caused to function hotlrearly and late indicates the percentage change from the normal vertical operation will be merely of the order of onethird of one per cent rather than of the order of sixteen per cent at the minimum as was the case for the horizontal shift above discussed. Accordingly, despite the inertia of the deflection circuits and the tendency thereof to maintain their normal state of operation, limited modifications of their periodicity can readily be effected without in any substantial manner upsetting the normal 0perational state. With limited percentage change in operation the so-called automatic frequency control methods of line deflection commonly used for black-and-white receiver operation at the present date are readily adaptable to control.4 This is not true for systems requiring a large percentage in the operational state of the line deflection generator.k It is usually desirable in color television operations to include automatic frequency control circuits in the receiver to maintain line frequency stability. Where color shift is effected by producing a control of the vertical scanning operation such stabilized circuits can easily be used. Further than this, the decreased burden of the receiver deflection circuits following rapid or large percentage changes in the state of operation tends to improve reproduced color quality. Still further, because of the fact that modifications in the nature of the horizontal deflection control are transferred to the slower-acting vertical deflection circuits, it is possible to obtain higher fidelity operation of a black-and-White receiver to which the color television transmission signals are supplied to re-create black-and-White image reproductions. This comes about through the improved operation of the stabilizing, clamping and D. C.restoring circuits at both the transmitter and the receiver.

Despite the fact that the color shift herein to be disclosed is brought about in the operation of the vertical circuit, it is nonetheless important to establish the timing of the color scanning operation. One way to achieve the result is that disclosed in the aforesaid U. S. patent application of George E. Sleeper, Jr. The color shift is brought about in accordance with this present disclosure by effectively changing the starting point of a color line scanning with respect to the viewing window or visible area of the re-created picture.

The color timing or' the color sync may be regarded as being dependent upon the starting of one color of the selected color sequence. This is because it is desirable to sync one particular color relative to the others. A suitable time to provide this result is following the shifted location of the vertical deflection pulses. At such time a signal defining one of the selected colors of the color cycle is transmitted. A signal of a character suitable for such purpose may be of the notched pulse variety set forth and described in tne aforesaid U. S. patent application of George E. Sleeper, Jr. A pulse of this character, illustratively, may be indicative of a so-called red scanning operation. The notched pulse, under these circumstances, may occur with precise regularity. Every third synchronizing pulse may be notched for line control scanning operation. Alternatively, this notched synchronizing signal control pulse (or an elongated synchronizing signal) may occur. only during the vertical blankng period. The control pulse is set to follow the selected form of vertical syncing signals. Still further, this type of color sync information may result from the selection in the receiver of a burst of highfrequency energy caused to follow from the transmitter after the transmission of the vertical synchronizing pulses. Selection of the color sync or the timing of the color also may be under the control of a widened pulse. Preferably the color sync starts coincidentally with a line deflection control pulse. The line sync pulse under consideration at this point follows the vertical control pulses but occurs during the vertical blanking period.

The present invention seeks to provide ways and means Many other objects and advantages of the invention of course will become apparent to those skilled in the art to which the invention is directed, when the following description and claims are read in connection with the accompanying drawings, of which:

Fig. 1 is a block diagram illustrating schematically a transmitter unit incorporating the invention;

Fig. 2 is a schematic block diagram of a television receiver incorporating the invention;

Figs. 3, 4 and 5 are exemplifications of color patterns in line sequential color television operations showing a picture consisting of seven lines only for illustrative purposes only, `as traced through seven successive fields, using zero shift, single shift and double shift respectively;

Fig. 6 is a schematic representation of waveforms occurring during the vertical blanking period for line sequential color television operations when single shift is employed;

Fig. 7 is a series of curves, also occurring during the vertical blanking period, to show a line sequential television operation during the vertical blanking period of six successive picture fields, when double shift is employed;

Fig. 8 is an expanded view of the color sync pulse which appears in the diagrammed illustrations of Figs. 6 and 7, as pulses substantially black in appearance;

Fig. 9 is a block diagram of the color shift control unit to operate in conjunction with the sync signal generator which is diagrammatically shown in Fig. l;

Fig. 10 is a circuit diagram illustration of one preferred circuit to include the vertical shift, the pulse standardizer or shaper and the buffer, schematically represented in Fig. 9;

Fig. 11 is a circuit diagram of the color sync generator representing a remaining portion of Fig. 9 and shows the colorhorizontal driving pulse circuit, together with the gating multivibrator and phase inverter;

Fig. l2 consists of a plurality of waveforms serving to indicate the operation of the circuit diagrammatically represented by Fig. 9 and represented circuitwise in Figs. 10 and l1. In this connection it may be noted that the waveforms shown by Fig. l2 are drawn for illustration of the operation, rather than precisely to scale, and, in some instances, for clarity of explanation, the polarities have been arbitrarily indicated and need not necessarily be as indicated;

Fig. 13 is a block diagram representative of the color receiver sync selection system; Fig. 14 is a circuit diagram illustrative of one form of lcircuit for operating in accordance with the broad principles of Fig. 13;

Fig. 1S is a series of waveforms likewise not necessarily to scale, and with arbitrarily chosen polarities to depict the operations of the receiver circuit of Fig. 14.

Making reference now to Fig. 1 of the drawings, there have been shown for illustrative purposes some of the more important components of a television transmitter pickup system. The unit 1 may comprise, for instance, the pickup camera to convert the optical images into video signals. It will be understood to include, for the purpose of illustration only, the deflection controls for the operation, the necessary preampliiiers, the line ampliiiers and the like. The output signals from this unit are intended to feed to a second amplifier 3, commonly known as the mixing amplifier. Operation of the pickup camera is established through the deflection control functioning under the influence and control of an appropriate form of sync signal generator depicted at 5. The sync signal generator is arranged to provide defiection control, so that the operation is in accordance with the Standards of Good Engineering Concerning Broadcast Stations as above mentioned, except insofar as modification is introduced by the color shift control unit 7. This color shift control will be more particularly explained in connection with the block diagram showing of Fig. 9, the circuit diagrams shown by Figs. 10 and 11, and the waveforms del amplifier 3. VThe mixed signals are appropriately combined to form the composite video and sync signal series prior to the control thereby of the schematically represented modulator 9. The modulator 9 may be assumed to include also the oscillator, the necessary R. F. amplifiers, the vestigial sideband filters and all other circuit components necessary to feed the R. F. signal either to an antenna or to any appropriate form of communication channel to feed out to receiver, relay or monitoring points. No power supplies have been indicated. The main function of Fig. `1 may be generally regarded as being that of showing the general relationship of the color shift control unit to the other components of a televisionY system designed primarily for color operation, although capable also of producing signals for black-and-white transmission, as has already been mentioned in the hereinabove reference to U. S. patent application of George E. Sleeper, Jr.

In Fig. 2 there has been shown in an extremely schematic form a television receiver (disregarding any audio components). This receiver is intended to be the form to re-create color television image patterns or rasters underV the influence of signals sent out from a transmitter such of Fig. 2 likewise will function to receive and reproduce television signals in black-and-white, where signals re-` ceived originate at a now-standardized black-and-white transmitter. The signals from the television signal channel, whether it be a cable, a relay or a radio source, may be received at the terminal 11 and supplied through an appropriate R. F. amplifier, oscillator and converter unit 13, for amplification in the video I. F. amplifier 15. The signals then are fed to the therewith associated demodulator.

The output from the demodulator is shown in Fig. 2 as feeding into a unit 17, which may be assumed to include thevideo amplifien'the D. C. restorer and the sync separator. Output signals from this unit are supplied to modulate the cathode ray beam produced within an imageproducing tube 19. Luminous effects resulting on the tube target area 21 may be considered to be intensity modulated in accordance with the radio transmission of signals from the pickup camera of Fig. l. Any appropriate method to cause the scanning cathode ray beam in the tube 19 to traverse the target may be utilized. Electromagnetic or electrostatic defiection, or a combination of both, is suitable. The sync signals are separated from the video signals in the unit 17. Separated signals are supplied to a portion of the circuit designated at 23. The

unit 23 can be assumed to include the deflection control.

and` phasing circuits. Such circuits serve, first, to estabthat of the transmitter, and, second, properly to phase the receiver operation with respect to the transmitter.

The unit depicted at 23 will be understood to include that component which is schematically represented by Fig. 13 and shown in one of its preferred forms in Fig. 14. The operation of such unit will be still further described in its operation by the curves of Fig. l5.

The showing of Fig. 2 is thus purely schematically illustrative. The vfigure has as its main purpose that of showing the relationship of certain receiver components to the unit as a whole.

It was above pointed out in the general statements concerning this invention that the control method provided was such that various shift patterns of color representation in a line sequential system might be produced. Purely as illustrative of this operation, reference may now be made to Figs. 3, 4-and 5, portraying zero shift, single color shift and double color'shift. In these gures the Roman numerals heading columns represent successively tracedfiieldsof-"thegfinally-produced image:pattern'L The 1 row designations represent the lines of themagcttracedin.

eacltifield.. The;letters1R', G and;;B respectively represent 1 the.y colors red,V green.y and:E blue; irraccordance` with whicheach line of the imageatthe:-transrnitterfisV analyzed and, the colorxrepresentatonreproduced at -re-v ceivng points.

Where-n0 color shifttrero shift) takes;place in the.l

line tracefrom field to field and the color cycle=is=assurned to v.be' in theorder of yred, green,'.bl\`1e,`redaand so on', the1 pattern ofFig. 3 mustnecessarilyresult, itx-it be assumed that the first line of .the picturecomingfwithin the-visibleY window (that is, outside.offthef-blankingfperiod) starts:

Turningnow. toFig. 4, a pattermutilizing .singl'e color shift. is'depicted. This term meansfthat eachi line iofthe. image; raster appears in at least two. colors .Within 1a ser. quence of each four field scannings: Considering' the image raster of Fig. 4, .linef l, for-:instances it .is .shown asredin Field Igit changes .to green in Field ill, and then returns to red in Field V. Similarly', raster line 2.appears asfblue in. Field Il; in. red .in Field lV; andl thenreturns. toA blue infield. Vl. Theecolor shifty orchangeetect is obtained .in .the .scanningl rasterfbychanging the .time at whichthe vertical deflection occurs witlznrespecttothe totaijnumberof lines tracedper eld..

With the zero color 'shift patternarrangementrof 'Figs 3, each. eld. deflection. occurs' precisely'at. the'end of 262Vz- 1ines of horizontal or line'deection.. In thefsingle color-shiftpatternof Fig; 4; forinstance, thefvertical ,dery iiecti'on .whichcauscs the productonzofFieldII follow-y ing .the scanning: of FieldI occurszafter'2621/2 lines. Following Field Il the line trace for Field III commences. onlyfafter 2631/2 lines of scanningxfollowing-the start oir; Field, Il.

start of Field V is only 2611/2 lines.

to present .black-andswhite standards) will; have. been traced inA the..v time f interval. between; thefcommeneement.

0f- .thLet-iirst andfo'urth field1scannings,x which 4is precisely4 the: number:` of. scanned' lines 5 fori four. -blackiandswhitee iieldscannings. However,- with acolorshiftToperation1in;

eiect the start of .anyoneiield'scanning with' respect to. that following or preceding may varyf within'. the zorder.

of one line; Aoroverla periodequal.to..H;.where;H*rep rescntszthe time between the 'start of1one-.linefscanningand' that line next following in. accordancewith thestandardsl of. Good Engineering Practice.` Concerning-r Televisioniy Broadcast Stations. so that the. color:shift'is.:ir1troduced;` Thefpattern` depictedby Fig. 5 isone showing one form of the I so-called'. double shift vcolor scanning operationiA whereinfollowing selected fields a `line-shift is made prior. to.. entering intov the next succeeding field.; Thissshift is either one or two lines, aheadaorbehind;vv torfprovidef.

the'color shift desired. In. thisway it Lwillabe'apparent that each line of,thefrastervor'patternis .tracedzin. each.. color within. a time period. occupied'bythe` scanning of: sixt".

picture fields (three picture frames). Many patternszor double shift are obtainable.l One other; such .pattern 'l`hescanningof`Fi'eld IV commencesat a' timefollowing 2621/2 .horizontal line'tracessubsequent to` the Vcommencement*of Field III., Lastly,'to .return to thestarting condition of Field. I, asthe'scanning enters Field V, the elapsed time between .the start of Field .IV andthe This` means that" irl-any fourpicture iields 1050 picture lines: (astreferredf:

- in known; manner.

lineasync, pulses: 31..

following` Field: III. mightV occur after' the scanningr-of 2621/2 lines .of ithe. raster or f scanningjpattern; thetvertical deflectionv followingField .IV might occur followingutli'eL scanning of52611/2 linesof the traced ipattern;following?` i Field V the indicated linetracewouldz appear ifthever# ticall deflection. took place afterv scanning2621/2 lines;and the vertical deflection of thel beam after the sixth'iieldlalsot-v mightoccur. following 2631/2 lines of the1tracedpattern, which would bring about ascanning patternforiFieldtVIIy precisely like Field l, after which the above-described conditions would be repeated.. The pattern; describedl.

hywFig. 5. isyto be. consideredpurely illustrativexoffotrc-.f of .those .whichmight be traced forydiierent formsofzthc' double; Y color. shift..

Reverting. now to; Fig. 6. of they. drawings,p the/.waveforms .thereshownv cover the general signal ,wavecpattem:; formation which occurs during substantially only'th'ezventical (field) blanking interval. In this ligure the,1 first. line'rshowsat theleft a line"synchronizingapulsewhich will control the starting of the last lineof the picturefiiel'd.4v

preceding .Field I.(this wouldbe a linetracedrinredaifi' referenceismade to Fig; 4).v Thewaveformxportiont 26 represents the video information for the last-scannedif line. of the field preceding Field I. The time period started'bytheequalizing pulse shown at 27 represents". vertical -blanking ln thisparticular ligure of ithedraw ingsthe signal polarity shown. extending in .the downward direction represents .that signalwhich wouldl produce-thev maximum carrier output at the transmitter. The-signal.. level indicated, at 231 representsblack in-the;pictur.e: so that thewaveform portion26 inthe particularinstancev shownisin the directiontoward highlights. in the'fpicturery Similarly, the line sync pulses 25 and the equalizinge pulses .2.7., asis customary inv illustrating` signalI .waveforms off-this character, are in the directionvof.maxirnutnsignalnv SOA-.that for the .system .transmitting black-and-white. Ythese.` would represent an intensityY blacker-thanfblack or! ultra-black. Inthis'particular waveform.y it can ybe seen thatzsix equalizing pulses 27 are. arranged to precedes-aa group .'of. six* elongated vertical. synchronizing -lpulsesrepg'- resentedy at. 29.

The figureA shades the. vertical sync pulsesl tofmakee them, readily identiable. They control. the verticalpdef iection .of the scanning cathode ray in---the.receivenstets-L liection after passing through Well-known integratingcitacuits... The 'elongated vertical sync rpulses 29,'. arelfollowed in the illustrated example by-eight -trailinglequalzs img pulses .prima tofthe transmission of, any, additional 25, th'e leading equalizing pulses 27, theverticalsync; pulses-29, the..trailing vequalizing.,pulsest)..and;the line syncpulses 31 is .precisely the.sameasin.blacleandwvhite.. transmission.y TheVV significant. difference. from.. black.. andai/hits.transmission. is that the vertical. syncpulsesv29 areffollowed. in .this instance vby eight.:equalizingpulses 30., rather than six for blackfand-white.

In `thedepicted'..illustration forthe red pattern. trace: inthe first line of Field I of Fig.. verticalblanking.Whichn `commences.- with thev first. equalizing pulse.: 27' com.

` ofillustratingthis invention, the blankingperiodbetween the..equalizingY pulse :.27 furthest ,to .the lefty and. .the..line.: sync .pulse 31 .furthest to the. right. may., be assumed .asx beinglequal to a peri0d-..of-.21H.or.8.%. of V. The.time.':

For the conditontshowmbya thisrline; .the:-.ior.m :of ;.signaljwaveformxdepietedtwill :ops l eraterthroughz; the usual..integratingtfcircuit.; toxcause athenl verticalzdeflection..circuit torfuncti'onf. and to .snapt/the.l

scanning: cathode ray L beann back? at 1 some selected-#times They usuallyexercise control ofde-v The. form of the...1ine.. sync .pulses during the period of production of the six elongated pulses. lThe precise time in the cycle when the snapback occurs may `vary slightly from receiver to receivery but remains generally constant at some point within the six long duration pulses for each individual receiver.

To phase the color operation a signal is developed fol lowing certain of the line sync impulses 31. The phasing signal is represented at 32. This phasing signal, as illustrated in Fig. 6, comprises a burst of high frequency oscillations. These signals may be developed from some local oscillator which is keyed once during each cycle of vertical deflection period. The pulses or oscillating waveform 32 may conveniently be in the form of a sine wave of a frequency of the order of about one megacycle which is keyed on and off once during each Vertical deflection field period. The phasing signal, when received at receiving points, operates together withthe horizontal or line sync signals, the equalizing pulses, and the vertical sync signals, to control the beam deflection in the image-reproducing tube. These signals control the scanning beam deflection and the color phasing circuits, as schematically depicted by Fig. 2 by the element 23. The various color shift patterns may *M- sult as desired.

Following the last line sync pulse 31 to the right of line I video signal information represented by the waveform 33 is then transmitted and continues through the remainder of the first picture field. With the last half line of video information in Field I represented at 34 opposite the designation II in this Fig. 6, the vertical blanking period again commences substantially concomitantly with the development of the first equalizing pulse 35l of the series following the first-scanned field. If the initially scanned line of the next eld traced (that is, line 2 of the first-produced picture frame) is commenced with blue no color shift in the line scanning order results. Accordingly, the sync pulses so occur that the vertical sync pulse series 36 follows six equalizing pulses 35 (as at the start of the first field). Again the vertical sync pulse is followed by eight equalizing pulses 37 and a certain number of line sync pulses 38 prior to the commencement of the visible transmissions which would follow the line sync pulse 39, the video information being depicted illustratively at 40. A phasing pulse consisting of a burst of high-frequency energy, for instance, may be used for color phasing as for Field I. Each'of the phasing pulses series 32 and 41 which are high-frequency energy bursts of like frequency may be considered to indicate the commencementof the red scanning operation (as one assumed form). The control may be established frornthe pulses selected under control of this particular wave series. This permits the color to interlace.

If reference is now made to Fig. l4 of the drawings, it will be noted that line 1 of Field III commences with a scanning of green in the picture, as contrasted to line 1 of Field I which started in red. This change to green in Field III represents a delay of one scanned picture or raster line (or an advance of two lines). To bring about such delay the vertical deflection control pulse series 42 shown on the third line of Fig. 6 opposite the designation III is preceded by eight equalizing pulses. This means that the vertical deflection control will not operate until a time period 4H susbsequent to the commencement of vertical blanking rather than a period of 3H subsequent thereto, as for Fields I and II above described. Following these general patterns and without changing in any way the color cycle of scanning the first line traced following the termination of vertical blanking and which linetracings are represented by the videosignaling information depicted at 44 would be represented in green in the picture rather than red, which would have been the case had vertical sync occurred in its normal time relationship'with respect to the first equalizing pulse. Consequently in scanning Field III the first line of the picture willbe scanned in green and the lines following will be in the'established color cycle. Referring' back again to Fig. 4 it can be seen that the color selected for tracing line 2 of Field IV is red (rather than blue which had appeared for line 2 in Field Il). This represents no color shift in the color scanning order, however, as can be observed. The vertical blanking period and the vertical sync deflection control provided by the signal series 45 occurs following precisely the same number of equalizing pulses as would the vertical sync signals for the third eld represented by line 3. Accordingly, the first line of signal traced in the next field will be indicative of red.

Field V will be repetition of Field l. color shift the vertical sync pulse series is shifted ahead one line period with respect to the field preceding. Consequently the scanning of the odd lines of Field V (commencing with line l) starts so as to correspond precisely to Field I and is thus like line l so that if the first line is red, and 'assuming the color cycle to be red, green, blue, red, and so on, as above, the odd lines of the picture will again be as per Field I explained above.'

Thus, to effect a single line shift in the Vpattern and provide a pattern traced of the type represented by Fig. 4, the block of six verticaly sync pulses may be shifted back and forth within the group of equalizing pulses which start at the commencement of vertical blanking and end at a time period 10H thereafter.y The period allotted to the leading equalizing pulses is in some instances 3H and in other instances 4H, with the period of trailing equalizing pulses under these conditions then being 4H and 3H, respectively. The long duration' vertical pulses are always of the same time period (3H) but shift over a one line 1H) period within the 10H period.

If now a double shift is used to arrive at a pattern where each line of each picture or raster trace is scanned in all colors, it will be appreciated that some portions of the cycle will have to have the color scanning order advanced one line to produce one of thecolors on one of the lines and advanced two lines (or retrogressed one line) to produce the same color on the same line even though it be at a later time period. For this purpose the period allotted between the commencement of the first leading equalizing pulse 47 within the vertical blanking time and the last equalizing pulse following the vertical sync pulses is lengthened into a period equal to 11H. To bring'about a one-line shift of ycolor or a two-line shift of color as the case may be, the group of six vertical equalizing pulses 48 is, as shown by Fig. 7, shifted as a group so that at one time the vertical'sync pulses may be preceded by six equalizing pulses 47 and followed by ten equaliz ingpulses 49; at anothertime the six elongated vertical sync pulses 48 may be preceded by eight equalizing pulses 47 and followed by equalizing pulses 49 of the same number and, still further, for the third condition the elongated vertical sync pulses may be preceded by ten equalizing pulses 47 and followed by six equalizing pulses 49. In

any case it amounts to a situation where control of the vertical deflection causes some individual color lines to be delayed, in effect, for a period of 1H `or 2H, as desired.

4Where the double color shift pattern is of the form shown by Fig. 5 the shift effect is somewhat similar to advancing the colors by a one-line period shift following each second field scanned. As an illustration of the condition it will be noted that the scanning pattern of Field I starts with line l in red, whereasthe scanning of the same line in Field III is in a green color. The change amounts to a shift of one line ahead (or two lines back) in the color cycle or sequence (such as the red, green, blue, red, and so on) above suggested. i Were there to be a zero shift, as per the pattern of Fig. 3, the lines of each field, e. g., Fields I, III, V and -so on for the odd lines and Fields II, IV, VI ,and so on for the even lines, would always appear in like color.`

This condition is brought about by the relative locay To achieve the t5 ingf'period and" thefY-rstzof the-'leading series of equalize ing'fpuls'es1'47.= Antadvancelvof one li'neis' equivalent to a delayv offtw'o' lines-fand'thereforefot-illustrative purposes" the' advance hasbeenselected.

The reverse'would be:equa1ly true, however, so that-by 5 an appropriate control ot`. the location in the vertical blanking-periodof the. group *t of'verticalpulses any desired'pattern might be'traced.' Fig. 7` shows the color phasingpulses 50 which'y are' of similar naturev to' those depicted at 41 byy Fig. 6'.: The phasingpulses() serve to allocate one' definitev color to the particular line of scanning followingthis-high frequency burst. The cil'- cuit'toa'chieve these yresults-will be more fully described in connectionv with thereference to Figs.A 9, 10 and' 11.

Referring to'fFig.` 8` fora moment, however, theres shown an expansion ofthe'bursts of high' frequency representing the phasing si'gnal'- burst, such as-v shown at 50- in-Fig.' 7. The waveform'v of signal depicted at 51 isf developed from a' sine-wavei oscillator which will be' referred to particularly-in connection with the descriptionv of Figs.' 9and'1l, although it will be noted at this time that the'high-frequency pulse'50 (enlarged'at 51), as shown', is not strictly sine wave due to a presenty inclusion in thel operational circuit of' suitable clippers throughwhich the sinewave signal is' passedprior to 2 transmission. InfFig'. 8 the' waveform represented oppo-v sitethe legend serrated pu1`se'is1illustrative ofthe fact that thehi'gh-frequency oscillator to'produce the phas-A ing signal burstfpasses-'through'=a reasonable numberA of oscillatory cycles each time the oscillator is' keyed to a usefully operative-state.- The'vgeneral relationship between this frequency'and' each' of t tl'ieA horizontal and the equalizing pulses-has been designated; Alternatively, th'e'high-frequency` energyf burstA represented in Fig. 8`- at' 51 might be replaced'by elongated signal 52, asv represented in the' second line-ofFig.' 8 oppositeth'e'legend widepulse Tlie-overall` effect of such pulse'reaching receiver instrumentalitiesI is generally like that obtain-A able with the' burst offliiglifrequency energy depictedv at 51. reasonably independent of ythe'amplitude at' which they' reach the'receiver for goodreceiver functioning. Theyhavel good noise rejectionfeatures'that do not disturbkv the operation of black-and-iwh-ite-receiversf because the black-and-white` receivers' would have been` caused'. to function' and tobe controlled as to'rate of horizontal'ory linedeliection by-'the leading edge ofy sync pulse imme-l diately preceding 4'the Aburst of' high-frequency energy for the widesignal pulse: The receiverfunctioning' with' either formVK of"colorfphia'sing signal willprovide" sub'-A stantially precisely accuratelyy controlled color represen'- tations.

Serrated'or high-frequencycburst'of signals '51, or'even the widesignal pulse 52,' mightibe-ireplacedby'a'notchedf form of-si`gnal,.such`, for instance, as that disclosed-byA` the'U.` S. patent application'S'erial No. 121,8"61` of George E. Sleeper, Jr., above''mentionedy Or, asuitable pulse for the controlpurpose might besl'oped at its -rearedge, for instance, or such a sloped pulse might be combined with :t notched pulse so that" the pulsehas the characteristicsY of'both the notch andthe slopingcrear 'edge: Such'signal formations alsowould'be reasonably 'independent ofiamplitude but would have-alesser degree of noise rejectionl than wouldth'osewaveformsdepictedfby,Fig. 8i Neither form of 'signal would have any=substantially deleterious-YI eect upon blackLand-white'@receiver operation'. Tliecost of operating circuitsto'selectv signals -'of"this character would'be only relatively: minor 'and of ItheV same generaly price 'range as those which will bedescribed as'particularly" applicable for the-signal wave'formationsvof Fig; 8."

Considering nowf circuits"particularly applicable'- forv producing and controllingcolr shift signalsl of such form' that 'the elongatediverticalsync pulses provide'ethe color selection, referencefmayfnow'fbe made4 to Fig;l 9-of"the' drawings: In-this #connection 'it i is" to be notedSthat-'the- In either instance-the twoforms'of signal are'40y Under these circumstances'the input signal at the input` terminal*v 54` is-alvpulse'repeated at the field frequency" ofv 60 cycles: per second, the pulse being of relativelyl short'duration compared to'the lo-second'eld periodi Thep'ulse' islusually'of a. duration something less thany 63:5-n'ricrosecondsr` (approximately the time required to scan one line' ofi S25-line, Bil-frame per second picture).

` The'diagrarn of Fig; 9 represents a bloclc form showing' of apparatus suitable'for controlling the signal forma ton suchY as torproduceY zero shift, single colorr shift' or double color'shift. Accordingly, the input pulse' at terminal 54 may be fed to all of a two-line delay multi# vibrator 55,- a one-line delay multivibrator 56, and a gate S71 The'two-linedelay multivibrator 55, in turn, feeds its output to a gate 5S'which is controlled in its operation ina manner later to be described by one output obtain-- able'I from a gate'multivibrator 59. The one-line delayv multivibrator 56" feeds its signal output to the gate-61 which is controlledin its operation by one output obtainable from the gate-multivibrator 62 which receives'it's controlsignal from the second output of the gatev multivibrator' 59. Eachfof the gates 57 and 6l supplies'out- 'l putsttdstill:anotherl gate 65 which latter element -is conf trol'led by the secondoutput signal from the gate multivibrator' 59; Thel output signals from the gate 58' and the gate 65V a're'supplied to a terminal marked D of a switch65`." Thegate'57 also supplies its output to the terminal Sito be 'contacted bythe arm of switch 66.

" resented by the'swi'tch` tl'and the contacts represented,

double"shift'of"the' pattern line traces is desired, switch' venience of'vreference, the so-far described'components .villf'be'termed the vertical shift circuit.

Referring to' Fig. 1.0 for circuit components like those so far described, the incoming input pulses attermin'al' point'i are fetlltothe two-line delay multivibrator which',

for'case 'of reference, may be considered as the tube 55 (inconsidering components'of this nature and to identify' the'components with'corre'sponding elements of'Fi'g; 9; elements such'fas-rnultivibratorswill have the tube/com-A ponents Ias vfar as vreasonably convenient bear similar or`- to the cathode 111 of the gate tube V58.

related numbers to the components of Fig. 9, although of course it is to be understood that the circuit components depicted, for instance, by Fig. are, of necessity, included within the blocks designated in Fig. 9). The incoming signals are applied, as above pointed out, in approximately the waveform indicated adjacent terminal points 54 in Fig. 10, so that the signal pulse itself extends into the negative polarity direction.

The multivibrator tube 55 is so connected that the grid of the left-hand section is normally held somewhat positive relative to the cathode by reason of its connection to the source of plate supply voltage available in the conductor 101, with the connection being made through the'resistor 102 and the potentiometer 103. This causes the tube normally to tend to draw current, so that the plate potential of the left-hand section is reduced from its plate supply potential, with the result that through the condenser 104 a potential which is negative relative to its previous state is applied. The grid of the right-hand half of the multivibrator tube 55 is held below cut-off by the time constant of the condenser 104 and the resistors 10S-106 which serve as the leak for the condenser. This state is maintained until the right-hand half of the tube conducts, when the plate potential then elective is transferred through the condenser 107, to the grid of the left-hand of the tube. A cycle of oscillations is thus maintained, subject, of course, to the input control pulse at terminal 54.

The time constant of the condenser 107 and the resistor combination 102-103 is such as to provide a pulse having a width equivalent to two black-and-white lines. The time constant of the condenser 104 and the resistors 105 and 106 is such that the grid of the right-hand half of the tube 55 is held negative relative to the cathode for a period longer than 1,60 second. If now a signal or pulse input is caused to appear at the terminal point 54, this pulse is applied through the resistor 108 and the condenser 109 in the negative sense through the condenser 107 to the grid of the left-hand half of the tube 55. The result is that temporarily this left-hand half of the tube is driven to a substantially non-conducting state, and the potential effective at the grid of the right-hand half of the tube is adequate to cause current to flow through that part of the tube. Consequently, a pulse extending in the negative direction is available at the right-hand plate. While the pulse applied at the terminal point 54 is of relatively short duration, and occurs at a rate of 60 cycles, in one form of operation the pulse amplitude may be of the order of 100 volts. Amplication occurs through the left-hand half of the tube, with the result that a voltage of amplified form is available to control the operation of the right-hand half of the tube. It can be seen from what has been explained that there is available at the plate of the right-hand half of the tube 55 a pulse extending in the negative direction. At the plate of the lefthand half of the tube there is a pulse extending generally in the positive direction, as shown by the waveform. This pulse is then transferred by way of the conductor 110 This tube is also supplied with a gating pulse from the multivibrator 59. which will be explained further in connection with Fig. 10.

The same pulse which is applied at the terminal pointV 54 is also supplied tothe multivibrator tube 56'` in a manner substantially similar to that described in connection with the two-line delay multivibrator 55 and the tube 55 thereof. The operation of the multivibrator tube 56 is generally similar to that described for the tube 55. It may be considered that the signal from the terminal 54 is applied through the resistor 112 and the condenser 113, to be eiective through the condenser 114 to control the grid potential on the left-hand half of the tube. This left-hand half of the tube, in turn, controls the operation of the right-hand half of the tube by reason of the connection 'of the condenser 115 having the leak resistors 116 and 117 connected between the grid and ground, as was explained in connection with the multivibrator tube 55. Normally, positive bias is applied to the grid of the left-hand half of the multivibrator tube 56 by reason of the connection to the positive voltage line 119 through the resistors 120 and 121. The output pulse available at the left-hand half of the tube 56' is supplied by way of the coupling condenser 122 to the cathode 123 of the gating tube 61. There is also supplied at this tube, as will later be explained, a further control pulse which is derived from the gating multivibrator 68.

Lastly, it was pointed out that the incoming pulses at terminal 54 were also supplied to a gate 57 which produced no delay. For convenience of operation, the gates 61 and 57 shown by Fig. 9 will be embodied within a single tube, as has been shown by Fig. 10 by the tube 61. The left-hand half of tube 61 forms the gate 61 of Fig. 9 and the right-hand half thereof forms the gate 57 or Fig. 9. Likewise, as has been explained in connection with Fig. 9, one output from the gate 57 and the output from the gate 61 are fed to a further gate 65. For convenience of operation and'for tube economy, the tube 58 may have its right-hand half function as the gate 58 and its left-hand half function as the gate 65. In this form it can be seen that the combined output from the gate tube halves has the left-hand half connected to the oneline delay multivibrator 56, while the right-hand half derives its signal directly from the incoming signal pulse at the terminal 54. Similarly, the output of the tube 61', as available at the plate or anode elements, is applied by way of the conductor 125 to the cathode element of the zero delay and one-line delay section of the gating tube 58 through the coupling condenser 126 (the left-hand half of the tube 58 functions as the gate 65 diagrammed in Fig. 9). The operation of these circuit components is such that the general form of pulse energy available at the outputs is somewhat like those waves depicted by F ig. l2. It can be assumed that the input wave available at terminal 54 is the wave (a) of Fig. 12. The output from the two-line delay multivibator which is shown at the output plate of the left-hand half of the tube 55 may be considered as the negative pulse shown by Fig. l2 by the waveform (c), delayed with respect to the applied pulse corresponding to ywaveform (a). The one-line delay pulse which is available at the output of the left-hand half of multivibrator tube 56 and which is supplied to control the one-line delay section of the gate 61' is schematically represented by the waveform (b) in Fig. 12. The drawing schematically shows the time of the various wave sections with respect to each other.

'It was explained above in connection with Fig. 9 that the gating multivibrator 59 serves to control both the gate 58 of the two-line delay circuit and the gating multivibrator 62, whose output, in turn, controls each of the gates 57 and 71. To this end the gate multivibrator 59 as shown by Fig. l0 comprises a pair of tubes 130 and 131, of which the former is a double triode and the latter is a double diode. The triode tube is connected essentially as a multivibrator of the general type above explained. It has its output as available atthe plate of the left-hand section supplied through the conductor 132 to the cathode of the left-hand'half of the gatingv tube 58', with the connection being made through the resistors 133 and 134. Accordingly, with the output of the multivibrator tube 130 extending alternately positive and negative, with the duration of each section measured by the time constant of the multivibrator circuit, the gating tube 5S may have its left-hand section pass current at times when there is coincidence between the negative pulse supplied to the cathode of the tube 53 through condenser 126 frorn the one-line delay and the zero delay gating tube 61 and the negative portion of the wave output from the gating multivibrator tube 130. Similarly, the right-hand half of the multivibrator tube 130 is connected avea-1st by way of the conductor 135 and the resistors 157 and 13S to the cathode of the right-hand half of the gating tube S so that at times when the gate of the right-hand half of the tube receives a negative pulse from both the two-line delay multivibrator tube 55 and the multivibrator tube 130, current will be passed through this portion of the tube.

The multivibrator tube 138 is controlled in its operation by a gating tube -in the form of the double diode 131. The multivibrator tube 139 as it is connected is generally of a type such that once an operation is initiated it is maintained.V if, for instance, the left-hand half or" the ultivibrator tube 136 were yto be drawing current, the plate potential thereof would be reduced, with the result that the potential effective at `the plate of the right-hand halt of the double diodev tube l1.31 would also be reduced from what it would be if the full voltage of the positive supply source lconnected through the conductor 141.- were to be available. Consequently, under the assumed condition, and due to the 'fact that the tube 130 is connected as a multivibrator, it is lapparent that if the left-hand half of the tube draws current, current will not be drawn by the right-hand` half. Under this assumption the plate or anode of Vthe right-hand half will assume the potential of the positive supply source connected in the conductor 141. The result is that this same potential becomes effective at the plate or anode of the left-hand halt of the double diode. Also, it will be noted from the connection shown that the cat hodes of each half of the double diode 131 connect together. Positive bias is applied through the resistor 142, sortlh'at generally neither half of the double diode tube 131 AcanI draw currei1t. lf, however, a control pulse is appliedt'oY the Adouble diode tube cathode through the conductor 143. and acbndenser 14d, it is lapparent that if this potential is in the negative sense, and of sufcient amplitude to overcome the positive `bias on the double diode cathode for the assumed state oftoperation, the left-hand half of the double diode will conduct. The result is that the potential there efective is transferred through the condenser 145 to the` grid of the left-hand half of the multivibrator tube 130 and current flow in this half of the tube is interrupted. Where the condition opposite that assumed above takes place, the right-hand half of the multivibrator tube 130 will draw current. The receipt of a negative ncontrol pulse impressedl by ".vay c-f the conductor 14'3'is such as to cause the right-hand halt of the double diode 131 to draw current. Consequently there would be transferred to the multivibrator' condenser 146 connected to the grid ofthe right-hand lhalf of the multivibrator tube 130 a negative potential suilicient to interrupt the curreritin this half Vof the tube. This multivibrator is generally a synchronized free-running type of circuit. The particular form of eircuitshown as comprising the tube 130 'and 131 is a general variation of the arrangement depicted on page 166 'oi the publication entitled W aveformsby Chance, Hughes, MacNichol, Sayre and Williams, forming vol. 19y Aof the Radiation Laboratory Series published by McGraw-Hill Book Co., inc., New York, 1949. Reference may be made to the aforesaid text for further description. The 'particular form of signal generation, and the particular waveform applied, will be referred to at a later point inthis description in connection with the description of the buffer arnpliiier, first with respect to Fig. 9 and later with respect to this Fig. l0. With the gating multivibrator 59, coinprising the tube 13.)k and the control double diode 131, functioningA` in they general manner explained, it will be apparent that a signal output therefrom serves to control the operation of the gate 53, both with respect to its control ori the output of the two-line delay multivibrator 55 and the gate 65 and with respect to its control of the output from the one-line delay multivibrator 56 as passed through the gate 61 and the output of the gate 57.

The outputsignal fromthe multivibrator tube 138, as controlled by the double diode tube 131 above described,

is also supplied (for double shift operation, with the ganged switches 66, 67 and '68 connected in the positions D indicated on the drawing for double shift operation) through the switch arm of the Vswitch 67 and the contact point D and the capacity element 151 to the cathodes of the double diode tube 152. with the connection being through the conductor 153. -As was above explained for the operation of the double diode tube 131.-, the cathodcs which are tied together are normally maintained positive relative to ground by way of the connection through thc conductor 153 and the resistor V154 to the source of positive voltage in the conductor 141. Accordingly, the double diode 152 normally does not draw current in either half, as was also explained in connection with the tube 131. The plates of the double diode 152 connect by way of conductors 1.55 and 156 to the `plates of the left- 'md right-hand halves of the multivibrator tube 157, which again is a unit which operates substantially like the tube elements above described at 131i. The arrangement of the multivibrator tube 157 is such that one half of the tube (that is, the left-hand half as shown) tends 'to draw current by reason of the connection of its grid element through the resistors 15S and 159 to a second source of positive potential appearing in the conductor 161. This again produces a condition similar to that explained above with respect to the tube 130, of which the grid in the left-hand section was normally held slightly positive by reason of the connection between the indicated resistor elements to the source of positive voltage available in thc conductor 141.

Under the assumed conditions, it will be apparent that with the left-hand half of the multivibrator tube 157 drawing current, the right-hand half ofthe tube will be blocked by reason of the connection ofthe multivibrator condenser 162 to the plate of the left-haad half of the tube. Of course, under these conditions, vthe plate of the left-hand half of the tube has its potential relativeto ground reduced by reasons of the current ow through the tube half. The result is that the plate or anode of the right-hand half of the double diode 15'2'assumes a like potential and, with the cathode biased positively, current does not ow in that 'half of the tube. Even though the 'right-hand half of the multivibrator 157 is not drawing current and the plate or anode thereof is at its lmaximum positive potential relative to ground and this potential is 'transferred to the plate and anode of the left-hand Ahalf of the double diode 152, the latter 4tube does not 'draw current in its left-hand half by reason of thepositive bias applied -to'the cathode. However, for this assumed state of operation it will be evident that if a pulse or other control voltage is applied to the cathodes ofithe double diode 152 through the conductor 153, the left-hand 'half of the double diode will first draw current. Consequently, the change in potential atv the left-handA plate of the double diode under such conditions would, ofcourse, be transferred to the left-hand half vof the multivibrator tube through the condenser 164. lCurrent liow inthe, left-hand half of the multivibrator tube '157 is interrupted, but ycurrent commences to flow in. the. right-'hand half of the double diode Vto operate at such times as a negative pulse is applied to the double ydiode cathodes.

The plate or anode of the right-hand half of the multivibrator'tube 157 -is connected 'by way of conductor 165 and resistor 166 to the cathode. 1'23'01? the gating tube 61. Likewise, the plate or anode of the left-hand half ofthe multivibrator tube 157'connects; through the conductor 167 and. the resistor -168v to the cathode of the right-hand half ofthe gating tube 61. Accordingly, vat time periods when pulses extending in the negative di'- rection lin either of the conductors 165 or 167 are'applied by way of condenser 122 to the cathode 123 simultaneously with a negative pulse on the conductor 165, it is apparent that the left-hand half'of the gatingtube 61 will draw current. The resulting negative potential at the plate is `then appliedby way of. conductor and the condenser 126 to the cathode of the left-handV half of the second gating tube 58. Likewise, the negative input pulses which are available at the terminal 54, when applied through the condenser 169 to the cathode of the right-hand half of the gating tube 61 concurrently with the application of a negative pulse to this cathode through the conductor 167, cause current to ilow in the righthand half of the gating tube 61'. The resultant voltage available at the plate also is transferred through conductor 125 and condenser 126 to the cathode of the left-hand half of the gating tube 58. This pulse functions to control that portion of the operation in which there is zero delay or one-line delay of the input signal as it leaves the tube. The gating of the gating tube 58' under `the control of the outputs from the multivibrator 130, as controlled by its associated double diode 131, has already been explained. Also, it has been pointed out that if the pulses applied from the multivibrator combination are in the negative sense with negative pulses concurrently applied to the left-hand cathode of the gating tube 58', current will ilow in the left-hand half of the tube. Likewise, if the pulses applied from the two-line delay multivibrator 55 by way of conductor 110 are negative on the cathode of the right-hand half of the gating tube 58' simultaneously with the application of controlling voltages by Way of conductor 136 from the multivibrator 130, there will be an output from the right-hand half of the gating tube 53'. This output then is made available on the conductor 173 connecting to the terminal point 174 of the switch 66. Such signals arethen supplied to a further multivibrator unit 175, which will be termed a pulse forming multivibrator, and which will form a part of a so-called pulse stabilizer.

At this point the description of Fig. encompasses all of the so far presented generalized description presented with respect to Fig. 9. Recapitulating in order to set forth the operation still further, those waveforms shown by Fig. l2 generally indicate the signals available at various points in the system, even though the Fig. l2 waveforms are largely schematic. More precisely accurate waveforms are shown at various points in the circuit of Fig. 10.

The controlling pulses available at terminal 54 are shown in Fig. 12 as the wave (a).l The output from the two-line delay multivibrator available as a negative pulse on the conductor 110 is shown as the waveform (c). The output pulses available in negative polarity at the output of the one-line delay multivibrator and which are used to control the left-hand half of the gating tube 61 are represented by the pulses (b) in Fig. 12. The control pulses (later to be described in detail and controlled from input source 201) which are supplied by conductor 143 to the controlling diode 131 in the double shift operation are indicated by the waveform (d). The output from the multivibrator 130 as available at the right-hand plate, and which is fed both by Way of the conductor 136 to control the gating tube 58', and by way of the capacitor 151 to control the double diode 152 is, upon receipt of the control pulses (d) on the double diode 131, a pulse in the negative direction, as indicatedv by the waveform (e). Since the multivibrator 130 is of such nature and has such a time constant as to provide the stated form of operation, the pulse extending in the negative direction is of half the duration of the pulse extending in the positive direction. The reverse-pulse polarity from the multivibrator 130 is available at the plate of the left-hand half of the tube. This pulse is applied through conductor 132. It is represented by the waveform (f) of Fig. 12. It will be seen that waveform (e) turns negative in polarity coincident with the receipt of the first of the pulses (d). Likewise, the waveform (f) turns positive in polarity coincidentally with the receipt of the first of the pulses (d). The next succeeding pulse (d) received brings about the opposite state of oper-ation of the multivibrator 130, so that pulses (e) and (f) are reversed in polarity.

This pulse relationship and position is maintained according to the illustrated example for the time period coinciding with the receipt of two successive pulses (d) or, in other words, for a 1/BO-Second period, after which the conditions again reverse. The multivibrator 157, as above explained, is triggered under the control of the double diode 152, which is, in turn, controlled by the output from the multivibrator 130. The result is that when the multivibrator 157 is operated, wave outputs such as represented by the waveform (g) are available on the conductor 165. A waveform output such as represented by the wave (h) is available at the conductor 167. This waveform, it will be seen, is such that an operational state which drives the left-hand half of the multivibrator 157 down to a substantially non-conducting state comes about, so that the wave (h) is available. The multivibrator operates in its assumed state until a second pulse of the controlling wave in the same polarity is received, at which time the operation of the multivibrator 157 is reversed so that the wave (h) then extends in the negative direction, while the wave (g) extends in the positive direction, and continues to reverse in accordance with the control exercised by the wave (e).

Now, for the condition of double shift operation, the wave (e), when in the negative sense, Will, if received on the cathode of the right-hand half of the gating tube concurrently with a pulse of waveform (c), cause the right-hand half of the tube to draw current. It can be seen from the diagram of Fig. 12 that the rst period of coincidence of negative polarity pulses (c) and (e) corresponds to the second from the left of the pulses (c). :Accordingly the first output pulse corresponding to wave (c) which is available from Ythe right-hand half of the gating tube 58 occurs as indicated by the wave (m). After the rst pulse from the left in the wave (m) is developed, the controlling wave (e) assumes a positive polarity until such a time that the fifth pulse (c) from the left in Fig. l2 is developed. At such time a second pulse in the waveform (m) is caused to be developed. This waveform is then applied by way of conductor 173 to the terminal 174 of the switch 66. However, since the output of the left-hand half of the gating tube 58 is also available at the terminal point 174 for double shift operation, it will be seen that if there is coincidencev in the time of receipt of a negative polarity pulse of waveforms (f) and a negative polarity pulse applied to the left-hand cathode of the gate tube S8' through the condenser 126, there will also be other outputs available at the terminal point 174. The signal available in the conductor 125, representative of one-line delay and zero delay as obtained from the gating tube 61', now depends both upon the polarity of the waveform (g), which is available from the multivibrator 157, and the polarity of the pulses (h), which have been delayed one line. It can be seen by reference to Fig. 12 that the waveform (g) is in a negative sense at a time coinciding with the second, third and fourth pulses (c) from the left. The result is that three negative pulses, represented by the wave (k) are supplied, due to the control of the left-hand half of the gating tube 61. Thus, if any of the pulses (k) which extend in the negative direction coincide with the negative portions Vof the waveform (f) on the gating tube 58', output pulses due to the one-line delay control will also be available at the terminal 174. These pulses are represented by the wave (n) of Fig. l2, where it will be seen that the waves (k) and (f) extend iu the negative direction concurrently at time periods corresponding to the time when the third and fourth pulses (b), for instance, are received.

Lastly, output may be available at the terminal point 174, due to zero delay control. These signals, which are determined by the periods of coincidence of the waves (h) .and (a) in negative polarity at the cathode of the right-hand half of the gating tube 61, will be as represented in waveform (n) by the pulses corresponding in 23 time to the rst, sixth and seventh 'pulses (a) Vavailable at 'the input terminal 54. The wave (n) is shown, thus, as a composite wave, due to the control exercised by the zero and one-line delay functioning-of the gating tube 61.

For summation purposes, the waveform (p) is indicated as that wave which is available at the terminal point 174, due to each of the waves (in) vand (it). It, therefore, is the summation wave.

It should be noted in this connection that the pulses in the wave (p) are Vall of precisely the same shape and available at the pulse standardize'r output. They are not uniformly spaced with vrespect to each other. The function of the shift circuit is to control, "as will become apparent at a later point hereof, precisely vthe time when the vertical deection is caused to oc'cur, as was made apparent from the description of the waveform shown by Fig. '7. Accordingly, it can be seen that from time to time the vertical waveform is in its position with respect to the initial equalizing pulse, as represented `by the`wave (.p).

If now single shift operation to produce a waveform which may be considered to have been illustrated by Fig. 6 is to be relied upon, the switch elements 66, 67 and 78 are all -rnoved to the contact .poin't- S. Under these circumstances, the output available at the terminal point 174 no longer can be supplied vto the switch arm `and therefore the final output signal is that signal which is available at the terminal 181. Consequently, the effect is as if the gating tube S serving to control in its lefthand half the combined output from the gates 57 and 61 of Fig. 9, and in its right-hand half the Vgate 58 of Fig. 9, can no longer control the operation. To the contrary, the output from the zero delay and one-line delay gatingtube 61 is supplied by way of the conductor 182 to the terminal point 181, with the result that the operation is slightly modified.

The pulse which is applied along the conductor 143 and through the capacitor 144 to the cathodes `of the double diode 131 is now, for the condition of single shift, also supplied by way of the conductor 182 tothe terminal point 133, upon which the arm of switch 67 rests. Under these conditions the incoming negative pulse in the conductor 143 will then besufcient vto control the operation of one or the other halves of the double diode tube 152. Control of the'op'era'tion of the multivibrator, of whichthe tube 157 forms a part, is'thus established. Operation of the multivibrator 157 under the influence of the doublediode 152 is, for single shift, determined by the signal pulses in the conductor 143 derived through the contact point 183 for the switch arm of the switch-67. This is incontrast to the control from the output of the multivibrator 130. Likewise, for the single shift operation, the switch 68 and the therewith associatedswitch 185 are moved from the Contact points "-D to the contact points 8. This shift inposition or the switch arms on the contact points serves t'o connect different values of the resistors between the conductor 161 and the grids of each half of the double triode type of multivibrator tube 157. The tube operation is 'thus established by the selected time constants.

It might be pointed out particularly at'thispoint that these grid resistors, such as those designated at 158 and 159 for the left-hand half of the multivibrator-tube 157 for a condition of double shift operation, function, at least insofar as the resistor 159 is concerned, for instance, in such a way as to avoid excessive 'capacity loading on the-tube. It also-serves as a current limiting element. The other resistors similarly positioned with respect to each half of the tube 157 yfunction-in asimilar mannen For conditions of single shift operation, the switch component`s187 and-188 will bemoved fromthe contacts D" to S, as indicated. lFor this condition the potential- `available on the conductor 161 'for double shift operation which is made available-entire conductor-189 24 is stillI available by reason of the joining of the switch contact .points S andl D.

For zero shift operation, still further changes become effective because the switchy arms of all switches 66, 67, 187 and 188 are moved over to the contact points 0. There is no connection in this operational state to provide for controlling the multivibrator 157 between pulses on the conductor 143. Also, no provision is made for applying any biasing voltage on the grids of either half of the tube 157. Likewise, forconditions of single and zero shift, changes in the operating voltages for various tubes in the system are provided. For all conditions of operationpla'te voltage for the tubes so far 'discussed is applied from the terminal point 190 by way of conductor 191 and the conductor 192. Under ya state of double shift operation each 'of conductors 161 and 141 receives 'operating voltage through the switches 187 and 188, since the switch arms connect -through lconductor 193 to receive the inputplate voltage from the terminal 190. Thus, all tubes in the 'system which have been discussed above in connection with 'the vertical shift circuit, namely tubes 56', 61', 585, 131, 130, 157 and 152, receive plate voltage from one or the other of conductors 141 and 161. Tubes 131 and 130 connect to the conductor l141 and tubes 157 'and 152 have their plates connected to the tube 161. The tubes 55 and 58' have their plates energized from conductors 101, which in turn connect by way of conductor 194 with conductor 141. The tubes 56 and 61' have their plates connected to the conductor 119, which connects by way of the conductor 195 to the conductor 161. Thus, for double shift operations, it will be-'s'een that all tubes above named can have their plates supplied from the terminal point 199 through one or the other of the conductors 101, 119, 141 and 161. However, `for single shift operation the conductor 141 is no longer connected with a positive input voltage source at the terminal l190, because the arm of the switch 188 is moved over to the contact point S. This change in connection removes the plate voltage from the double diode 131 and the multivibrator tube 130. It also removes plate voltage from the multivibrator tube 55 and the double diode 58 Other tubes of the system, namely 56', 61', I157 and 152 now receive plate voltage by reason of the fact that the switch arm of switch 187 connects to its contact points S.

Accordingly, all units functioning only with double shift operation are rendered inoperative when the switches are moved to the single shift position S.

Similarly, as a condtion of zero shift operation cornes about, the'move'ment-of the switch arms 187 and 188 to the 'Contact points O immediately removes operating voltage from all of the tubes abov'e discussed. It thus renders the already-described portion of the system concerned with double'and single Vshiftinoperative, except for the fact that the input pulses which appear at the input terminal 54 are transferred through the conductor 199 to the switch point 0, whereupon the switch arm of switch 66 comes to rest. Output voltages are then applied tothe grid of the left-hand half of tube in thc same manner as would have been the case had the switching operation not occurred.

The arrangement thus described accordingly functions to provide flexibility in the type of synchronizing signal utilized, because shifting the position of the control switches between the terminals D, S and O determines'whether double shift, single shift or zero shift operation has been provided. Thus, the form of synchronizing waveform Atransmitted to receiving points is determined.

Mention has been made above of "the control pulse 'supplied't'o'theconduct'or 143 vfor the purpose of triggering'themultivibrator tubes 130 and/or 157 by way of the Vdouble diodes 131 and/or 152. The pulses from which 'the v"control voltagesflon the conductor 202 are vdeveloped aire-:supplied at theinput terminal point201 

